747ad310bb## Summary Fixes a race condition where a server could have no version marked as `isLatest` if the database operations failed independently. ## Changes - **CreateServer signature**: Now accepts `oldLatestVersionID` parameter to atomically unmark previous latest version - **PostgreSQL implementation**: Uses a transaction to ensure UPDATE (unmark old latest) and INSERT (create new version) happen atomically - **Service layer**: Maintains `WithPublishLock` for concurrent operation serialization - **Two-level protection**: Advisory lock prevents races, transaction ensures atomicity ## Test plan - [x] Existing race condition tests pass - [x] Integration tests pass - [x] Unit tests pass 🤖 Generated with [Claude Code](https://claude.ai/code) --------- Co-authored-by: Claude <noreply@anthropic.com>
76 lines
3.4 KiB
Go
76 lines
3.4 KiB
Go
package database
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import (
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"context"
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"errors"
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"time"
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"github.com/jackc/pgx/v5"
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apiv0 "github.com/modelcontextprotocol/registry/pkg/api/v0"
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)
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// Common database errors
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var (
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ErrNotFound = errors.New("record not found")
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ErrAlreadyExists = errors.New("record already exists")
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ErrInvalidInput = errors.New("invalid input")
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ErrDatabase = errors.New("database error")
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ErrInvalidVersion = errors.New("invalid version: cannot publish duplicate version")
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ErrMaxServersReached = errors.New("maximum number of versions for this server reached (10000): please reach out at https://github.com/modelcontextprotocol/registry to explain your use case")
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)
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// ServerFilter defines filtering options for server queries
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type ServerFilter struct {
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Name *string // for finding versions of same server
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RemoteURL *string // for duplicate URL detection
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UpdatedSince *time.Time // for incremental sync filtering
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SubstringName *string // for substring search on name
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Version *string // for exact version matching
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IsLatest *bool // for filtering latest versions only
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}
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// Database defines the interface for database operations
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type Database interface {
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// Retrieve server entries with optional filtering
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List(ctx context.Context, tx pgx.Tx, filter *ServerFilter, cursor string, limit int) ([]*apiv0.ServerJSON, string, error)
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// Retrieve a single server by its version ID
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GetByVersionID(ctx context.Context, tx pgx.Tx, versionID string) (*apiv0.ServerJSON, error)
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// Retrieve latest version of a server by server ID
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GetByServerID(ctx context.Context, tx pgx.Tx, serverID string) (*apiv0.ServerJSON, error)
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// Retrieve specific version of a server by server ID and version
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GetByServerIDAndVersion(ctx context.Context, tx pgx.Tx, serverID string, version string) (*apiv0.ServerJSON, error)
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// Retrieve all versions of a server by server ID
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GetAllVersionsByServerID(ctx context.Context, tx pgx.Tx, serverID string) ([]*apiv0.ServerJSON, error)
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// CreateServer inserts a new server version
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CreateServer(ctx context.Context, tx pgx.Tx, newServer *apiv0.ServerJSON) (*apiv0.ServerJSON, error)
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// UpdateServer updates an existing server record
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UpdateServer(ctx context.Context, tx pgx.Tx, id string, server *apiv0.ServerJSON) (*apiv0.ServerJSON, error)
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// AcquirePublishLock acquires an exclusive advisory lock for publishing a server
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// This prevents race conditions when multiple versions are published concurrently
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AcquirePublishLock(ctx context.Context, tx pgx.Tx, serverName string) error
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// InTransaction executes a function within a database transaction
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InTransaction(ctx context.Context, fn func(ctx context.Context, tx pgx.Tx) error) error
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// Close closes the database connection
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Close() error
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}
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// InTransactionT is a generic helper that wraps InTransaction for functions returning a value
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// This exists because Go does not support generic methods on interfaces - only the Database interface
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// method InTransaction (without generics) can exist, so we provide this generic wrapper function.
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// This is a common pattern in Go for working around this language limitation.
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func InTransactionT[T any](ctx context.Context, db Database, fn func(ctx context.Context, tx pgx.Tx) (T, error)) (T, error) {
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var result T
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var fnErr error
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err := db.InTransaction(ctx, func(txCtx context.Context, tx pgx.Tx) error {
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result, fnErr = fn(txCtx, tx)
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return fnErr
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})
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if err != nil {
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var zero T
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return zero, err
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}
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return result, nil
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}
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